week 5 Flashcards
describes the ability of a drug to kill or inhibit pathogens while damaging host as little as possible
a. selective toxicity
b. therapeutic dose
c. toxic dose
d. therapeutic index
selective toxicity
Which of the following statements best differentiates narrow-spectrum and broad-spectrum antibiotics?
a) Narrow-spectrum antibiotics target only Gram-negative bacteria, while broad-spectrum antibiotics target only Gram-positive bacteria.
b) Narrow-spectrum antibiotics are effective against specific types of bacteria, whereas broad-spectrum antibiotics affect a wide range of bacterial species.
c) Broad-spectrum antibiotics are always more effective than narrow-spectrum antibiotics.
d) Narrow-spectrum antibiotics have more side effects compared to broad-spectrum antibiotics.
Narrow-spectrum antibiotics are effective against specific types of bacteria, whereas broad-spectrum antibiotics affect a wide range of bacterial species.
what is the difference between MIC and MLC?
a) MIC is the lowest concentration of a drug that kills bacteria, while MLC is the lowest concentration that inhibits bacterial growth.
b) MIC is the lowest concentration of a drug that inhibits bacterial growth, whereas MLC is the lowest concentration that kills the bacteria.
c) MIC is always higher than MLC for any given antibiotic.
d) MIC measures bacterial death, while MLC measures bacterial reproduction rate.
MIC is the lowest concentration of a drug that inhibits bacterial growth, whereas MLC is the lowest concentration that kills the bacteria.
Which of the following best describes selective toxicity in antibiotics?
a) The ability to kill all types of microbes equally
b) The ability to inhibit or kill pathogens while causing minimal harm to the host
c) The ability to stimulate the immune system to fight infections
d) The ability to remain stable at all pH levels
The ability to inhibit or kill pathogens while causing minimal harm to the host
Which of the following tests is used to determine the minimum inhibitory concentration (MIC) of an antibiotic?
a) Disk diffusion test/kirby bauer
b) Gram staining
c) Dilution susceptibility test?
d) PCR analysis
dilution suspectibility test
MIC is determined by finding the lowest concentration that inhibits bacterial growth.
What is the primary mode of action of beta-lactam antibiotics, such as penicillins and cephalosporins?
a) Inhibition of protein synthesis by binding to ribosomes
b) Disruption of nucleic acid synthesis
c) Blocking of cell wall synthesis by preventing peptidoglycan cross-linking
d) Inhibition of folic acid metabolism
Blocking of cell wall synthesis by preventing peptidoglycan cross-linking.Beta-lactam antibiotics disrupt bacterial cell walls, leading to lysis.
Why is vancomycin considered an important antibiotic in clinical settings?
a) It has a broad spectrum and can kill all bacterial pathogens
b) It specifically targets viruses and fungi
c) It is effective against antibiotic-resistant Gram-positive bacteria such as MRSA
d) It enhances bacterial growth under laboratory conditions
It is effective against antibiotic-resistant Gram-positive bacteria such as MRSA.Vancomycin is crucial for treating resistant bacterial infections.
Which of the following statements about antimicrobial resistance is correct?
a) Resistance genes can only be passed from parent to offspring (vertical gene transfer)
b) Bacteria can acquire resistance through horizontal gene transfer, such as conjugation and transformation
c) Resistance only develops when antibiotics are not used
d) Antibiotic resistance is irreversible once acquired
Bacteria can acquire resistance through horizontal gene transfer, such as conjugation and transformation.Resistance spreads through genetic exchange mechanisms.
What is the key difference between bacteriostatic and bactericidal antibiotics?
a) Bactericidal antibiotics kill bacteria, while bacteriostatic antibiotics inhibit their growth without killing them
b) Bacteriostatic antibiotics kill bacteria, while bactericidal antibiotics only inhibit growth
c) Bacteriostatic antibiotics work only on Gram-positive bacteria, while bactericidal antibiotics work on Gram-negative bacteria
d) Bactericidal antibiotics function by inhibiting folic acid synthesis, while bacteriostatic antibiotics disrupt protein synthesis
Bactericidal antibiotics kill bacteria, while bacteriostatic antibiotics inhibit their growth without killing them.Bactericidal drugs lead to bacterial cell death, whereas bacteriostatic drugs stop bacterial growth.
Which of the following best explains why biofilms contribute to antibiotic resistance?
a) Biofilms decrease bacterial mutation rates
b) Bacteria within biofilms can communicate and become dormant, making them less susceptible to antibiotics
c) Biofilms promote antibiotic absorption and increase effectiveness
d) Biofilms reduce genetic diversity, making resistance genes less common
Bacteria within biofilms can communicate and become dormant, making them less susceptible to antibiotics.Biofilms create a protective environment that reduces antibiotic effectiveness
Why is it important to complete a full course of antibiotics as prescribed?
a) To ensure the body builds long-term immunity against the bacteria
b) To prevent the surviving bacteria from developing resistance due to incomplete treatmen
tc) To allow the drug to stay in the bloodstream permanently
d) To avoid interactions with future medications
To prevent the surviving bacteria from developing resistance due to incomplete treatment.Stopping treatment early allows partially resistant bacteria to survive and multiply.
Which of the following antibiotics works by inhibiting DNA gyrase and topoisomerase II?
a) Penicillin
b) Tetracycline
c) Ciprofloxacin
d) Erythromycin
Ciprofloxacin.
Ciprofloxacin inhibits DNA gyrase and topoisomerase II, preventing bacterial DNA replication.
involves inoculating media with different concentrations of drug, and the lowest concentration that shows no growth is the MIC
a. dilution susceptibility test
b. Kirby Bauer test
dilution susceptibility test
Prepare tubes or plates with increasing concentrations of the antibiotic.
Inoculate each with the same amount of bacteria.
Incubate and observe for bacterial growth.
The lowest concentration with no visible growth is the MIC.
To find the MLC, transfer samples from MIC tubes to antibiotic-free media. If bacteria don’t grow, that concentration was lethal.
What is the primary purpose of the disk diffusion (Kirby-Bauer) test?
a) To determine the minimum concentration of an antibiotic that inhibits bacterial growth.
b) To measure the ability of bacteria to produce enzymes that degrade antibiotics.
c) To assess the effectiveness of different antibiotics by measuring zones of inhibition around antibiotic-impregnated disks.
d) To identify the genetic mutations responsible for antibiotic resistance.
To assess the effectiveness of different antibiotics by measuring zones of inhibition around antibiotic-impregnated disks.
bigger zone of inhibition=bacteria are more susceptable to the antibiotic.least resistant
what do antibiotics target/inhibit/reduce? (4)
- cell wall synthesis
- protein synthesis
- metabollic processes
- nucleic acid synthesis
how do organisms gain resistance to bacteria?
microbial warfare (competition releases antibiotics to outcompete other organisms)
horizontal gene transfer
evolutionary pressure from widespread antibiotic use
Why is antibiotic resistance a major global health concern?
A) Resistant bacteria grow slower and are easier to treat.
B) Antibiotic resistance reduces the effectiveness of treatments, making infections harder to control.
C) Resistance genes cannot spread between bacteria, limiting their impact.
D) The overuse of antibiotics has no effect on bacterial evolution.
Antibiotic resistance reduces the effectiveness of treatments, making infections harder to control.
Antibiotic resistance makes infections harder to treat because bacteria can survive exposure to antibiotics. This leads to longer illnesses, higher medical costs, and increased mortality. Resistance genes can spread between bacteria through horizontal gene transfer, and widespread antibiotic use accelerates evolutionary pressure, promoting resistant strains. sometimes resistant mutants arise spontaneously
a narrow spectrum of antibiotics that only work on gram positive bacteria:
a. halogens
b. Vancomycin and Teicoplanin
c. Penicillins (β-lactam)
d. Cephalosporins
Penicillins (β-lactam)
what is the role of Penicillins (β-lactam):
a. blocks the enzyme that catalyzes transpeptidation
(formation of cross-links in peptidoglycan)
b. prevents the synthesis of complete cell walls leading
to lysis of cell
c. acts only on growing bacteria that are synthesizing
new peptidoglycan
d. Inhibit gene expression
blocks the enzyme that catalyzes transpeptidation
(formation of cross-links in peptidoglycan)
acts only on growing bacteria that are synthesizing
new peptidoglycan
prevents the synthesis of complete cell walls leading
to lysis of cell
